Pneumatic door-check



(No Model.)

J. A. SHERMAN.

V PNEUMATIC DOOR GHEGK. No. 298,787. Patented May 20, 18 84.

55-1125. Irp/qhnr. W"- @M N. PETERS. Phom-umu n m Wi liam 0.0.

Uirnn rarns PATENT tries.

JOHN A. SHERMAN, OF BOSTON, MASSACHUSETTS.

PNEUMATIC DOOR CHECK.

PECIFICATION forming part of Letters Patent No. 298,787, dated May 20,1884. Application filed August 13, 1883. (No model.)

To aZZ whom, it may concern Be it known that I, JOHN A. SHERMAN, ofBoston, county of Suffolk, and State of Massachusetts, have invented anImprovement in Automatic Door-Ohecks, of which the followingdescription, in connection with the accompanying drawing, is aspecification, like letters on the drawing representing like parts.

My invention relates to a door-check of that class in which a cylinderis employed in connection with a piston and actuating-spring, the saidpiston and cylinder being connected with the door and door-frame in suchmanner that the force of the spring acting on the piston tends to closethe door, and the movement of the parts is checked or cushioned by airtrapped between the piston and cylinder, to thus prevent the door fromslamming.

The present invention consists, mainly, in a novel construction andarrangement of the -connecting mechanism between the said piston andcylinder and the door and its frame, as will be hereinafter described.

The drawing represents in plan view a door, and in section a portion ofits frame, provided with a door-cheek embodying this invention, theparts being shown in full lines in the position assumed when the door isclosed, and in dotted lines in the position assumed when the door ispartially opened.

The cylinder a and the piston I) and actuating-sprin g 0, (shown indotted lines,) and the valve or device in the cylinder-head d, forcontrolling the escape of air from between the said piston andcylinder-head, are all substantiallythe same as in door-checksheretofore in use, and consequently do not need any detaileddescription.

The cylinder-head (Z is provided with a lug, at, extending along theside of the cylinder a short distance from the end thereof, and pivotedupon a pivot-plate, 6, adapted to be rigidly fastened upon the door orits frame, and the piston-rodf has an extension, 1'', forming anintegral part thereof, which is turned back at the side of the cylinderand pivotedat it upon the said pivot-plate c, a short distance from thepivotal point (1 of the cylinder, so that when the said cylinder andpiston-rod are turned on their pivot-points d and h in the direction ofthe arrow 2 the piston-rod f will be moved away from the cylinder-headd,

compressing the actuating-spring c, which is interposed between thepiston and the oppo site cylinder-head. The cylinder and pistonrod arecaused thus to turn on their pivotal points to compress the spring 0when the door is opened by means of aconnecting-bar, i, pivoted to thepiston-rod f at m and to the doorframe at a, if the pivot-plate c isattached to the door 5 but if the pivot-plate were attached to thedoor-frame the connecting-bar t would be pivoted. to the door.

It will be seen that the hinge or axis of movement of the door and thepivotplate e and connecting-bart' are in such position with relation toone another that as the door is turned on its hinge the cylinder andpiston-rod are rocked on their pivot-points d and h, and the piston Z)is thus moved through the cylinder. In this movement air is introducedbetween the piston and cylinder-head d, in the usual manner, and theactuating-spring c is compressed, so that as soon as the door isreleased by the person who openedg it the said spring will tend to forcethe piston back through the cylinder, thus restoring the parts to theirnormal position (shown in full lines) and closing the door, the aircontained between the piston and cylinder-head d checking and cushioningthis movement so as to prevent the door from slamming, in the usualmanner.

Door-checks have been made previous to my invention in which thecylinder is pivoted at one side of its extreme end upon a pivotplate atsubstantially the same distance from the door as the pivotal point ofthe cylinder. By pivoting the cylinder at a short distance from its end,as herein shown-or, in other words, by making the pivotal point of thecylinder at a greater distance from the door than that of the extensionof the piston-rod a greater throw of the piston in the cylinder isproduced, and the piston-rod is caused to travel more freely through thecylinder-head, thus reducing the wear of these parts;

By making the piston-rod and its extension of a single piece, as hereindescribed, the construction of the apparatus is simplified and its costreduced without detriment to the op eration.

The distance from the pivot-plate of the pivotal point (1 of thecylinder beyond the pivotal. point it of the piston-rod extension isbetween the piston-rod and its extension.

I claim- The cylinder and piston and piston-rod provided with anextension combined with the pivot-plate to which the said cylinder androdextension are pivoted, the pivotal point of the cylinder beingfarther from the plate than that of the rod-extension by a distanceabout equal to that between the said pivots measured parallel with theplate, substantially as and for the purpose set forth.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

JOHN A. SHERMAN.

Vitnesses:

J os. P. LIVERMORE, W. H. SIGsToN.

